Possible astrometric discovery of a substellar companion to the closest binary brown dwarf system WISE J104915.57-531906.1

Boffin, H. M. J.; Pourbaix, D.; Muzic, K.; Ivanov, V. D.; Kurtev, R.; Beletsky, Y.; Mehner, A.; Berger, J. P.; Girard, J. H.; Mawet, D.
Astronomy & Astrophysics, Volume 561, id.L4, 5 pp. (2014).


Using FORS2 on the Very Large Telescope, we have astrometrically monitored over a period of two months the two components of the brown dwarf system WISE J104915.57-531906.1, the closest one to the Sun. Our astrometric measurements - with a relative precision at the milli-arcsecond scale - allow us to detect the orbital motion and derive more precisely the parallax of the system, leading to a distance of 2.020+/-0.019 pc. The relative orbital motion of the two objects is found to be perturbed, which leads us to suspect the presence of a substellar companion around one of the two components. We also perform VRIz photometry of both components and compare with models. We confirm the flux reversal of the T dwarf.

Based on data obtained with the ESO Very Large Telescope under programme 291.C-5004.Figures 2 and 3 and Table 3 are available in electronic form at